Soak the wakame in cold water, then drain well. Slice the spring onions into thin rings.
Heat the water in a pan, then just keep it gently hot. It shouldn't boil hard.
Carefully cut the silken tofu into small cubes. Stir the miso paste with a little hot water in a small bowl until smooth.
Add the dissolved miso paste to the pan and stir it in. Add the tofu and wakame and leave everything to steep briefly.
Season with soy sauce. Don't let the soup come back to a rolling boil, so the flavour and texture stay delicate.
Ladle into bowls and serve with the spring onions.
Good to know
This soup is quiet, warm and on the table in a few minutes. It tastes clear, savoury and pleasantly light.
Swaps
Silken tofu → firm tofu (more bite, similar protein); wakame → nori strips (milder seaweed flavour, also contains iodine in variable amounts); soy sauce → tamari (often gluten-free, similarly savoury); spring onions → chives (milder, also provides a little vitamin K)
Allergens
Contains soya and, depending on the soy sauce, gluten too. Generally fine for children and during pregnancy, but better in moderate amounts because of the salt content and the iodine from seaweed.